This invention relates to a device for the separation of a load from a belt assembly to which it is attached and particularly to the release of a load suspended from a parachute on impact with the ground. More specifically, the present invention is directed to apparatus for releasably coupling a load to straps by which it is suspended, the coupling mechanism including an impact component which is affixed to the load on the side of expected impact, the coupling mechanism being operated by the movement of at least a part of the impact component relative to the load in response to an impact such as will occur when a load suspended from a parachute strikes the ground.
Published Federal Republic of Germany patent application DE-AS No. 19 48 543, discloses a prior type of release coupling for use between a load and a parachute, this prior coupling being provided with a pyrotechnic separation device which is detonated in response to the forces produced when the load strikes the ground. This type of releasable coupling device has the disadvantages that it is expensive and likely to malfunction both because of the reliance upon an auxiliary energy source for operation and because of the relatively large number of components disposed between the member which receives the impact and the separating coupling. Pyrotechnic separation devices further have the disadvantages of susceptibility to destruction, for example a premature detonation, and the fact that there is a delay between impact and operation of the release mechanism.
Releasable coupling mechanisms for suspended loads are also known which do not require use of auxiliary energy and on landing of the load operate in response to deceleration thereof or a reduction in the force acting on the coupling mechanism. Devices of these types are disclosed in Federal Republic of Germany Published patent application Nos. DE-AS 1 226 884, DE-OS 29 49 452, DE-AS 25 03 936, DE-OS 25 52 935, DE-OS 28 34 435. In order that such couplings are not unintentionally released in response to dynamic forces occurring during descent, they must have a high control threshold or suitable safety components which delay the operation of the coupling mechanism to thus prevent premature release of the load in response to transient conditions. These types of coupling mechanisms have the disadvantage that they are located at the upper part of the load so that during the launch or landing the releasable coupling mechanism can fall on the load and damage it. Finally, such coupling mechanisms have the disadvantage that, after the release of the separation coupling, most or some of the belt assembly remains connected to the load and can damage it.
The general object of the present invention is to provide a coupling mechanism particularly well-suited for joining a parachute assembly to a suspended load which is operable without delay and which, on landing, safely and reliably releases the belt assembly by which the parachute is connected to the load, especially on a hard landing.
According to the present invention, the releasable coupling mechanism is designed such that the belt assembly is directly released in response to movement, caused by the force of impact, of at least a part of an impact component relative to another component of the coupling mechanism which is affixed to the load.
The direct utilization of the force of impact eliminates the need for a source of auxiliary energy and also the need to take into account variations in the force applied to the releasable coupling mechanism during descent. The operation of the present invention is such that any frictional losses occurring in the coupling mechanism will be overcome by the forces produced upon impact of the impact component with the ground.
According to the present invention, the releasable coupling mechanism is comparatively inexpensive, this being particularly true when it is recognized that the impact component serves the dual function of a landing shock absorber. The required motion of the impact component relative to the load as the impact component performs the shock absorbing function may thus be used as separating motion for the union of the load with the belt material assembly by which the load is connected to the parachute assembly.
Since the load may arrive at the ground in a slanting position, the impact component is constructed so as to define a plate which functions as an extended edge of the load upon which impact will occur. This plate-like impact receiving member is mounted such that the required motion of the impact component with respect to the load will occur regardless of the point on the edge of the load where contact is first made with the ground.
According to the invention, the connection of the load to the belts or straps by which the load is suspended from the parachute is implemented by the interconnection of plural belt ends. This permits the coupling of the belt assembly to the load solely by external binding of the load and without the need for a binding component or the like which supports the full weight of the load. The interconnection of the belt ends is easy to implement and to break. The interconnection technique of the present invention has the desirable attribute of allowing the impact component to be located in close proximity to the point or region of interconnection of the belt ends and this, in turn, permits the means by which force and motion is transferred to the mechanism by which the interconnection is broken to be of uncomplicated construction.
According to the invention, the interconnection of the belt ends is preferably defined by a destructible connecting link. In an advantageous specific embodiment, this connecting link cooperates with a separating or disrupting mechanism in the form of a knife which moves in response to movement of all or part of the impact component. As an alternative, the connecting link is comprised of a material which fractures upon transferral of the impact force from the impact component. For example, the connecting link can consist of a connecting ring which cooperates with the belt ends and which is comprised of brittle material such as glass which, when subjected to sufficient stress or force, will shatter so that the belt ends are freed.
According to another embodiment of the invention a connecting link, for example a pin, which is displaceable by the force of impact out of a location where it engages loop extensions of the belt ends to a location in which the belt ends are released from one another. In this arrangement the impact induced displacement of the separating connection or member, which displacement is in a direction which is generally transverse to the ends of the belts to be released, permits the connecting link(s) to be pulled free of the belts.
According to an important feature of the invention, the connecting link for the belt ends may comprise a single easily destructible member and thus the decoupling or belt end separating function may be performed as a single step. Accordingly, the collected belt ends may be simultaneously detached in a single procedure.
An example of an embodiment which implements such a single step function release has a cord which connects the collective belt ends and on impact is separated by at least a cut. The connecting link may be generally star-shaped and defined by a cord which intersects itself in a central region and in this embodiment the knife is ring-shaped and located adjacent the region of the intersection of the rope. The proper location of the ropes inside of the region circumscribed by the knife is obtained by rigidly connected guide parts for the cord and the knife on that portion of the coupling mechanism which is affixed to the load.
The single step release operation is also implemented by the displacable connecting link embodiment which employs a retaining finger which extends through several connecting belt ends or loop-like extensions thereof. On impact the retaining finger, which is resiliently biased to the belt end engaging position, is caused to be retracted whereupon the retaining finger is withdrawn from the belt ends.
In the present invention the belt-end separating arrangement is concentric to the generally plate-shaped impact component and the impact component is fastened to the load in such a way that upon impact at least a portion of an edge region thereof approaches the load to thereby actuating the separating mechanism. This motion of the impact component as a result of the stressing of a point on its edge is permitted by supporting the impact component on its edge by a retaining arrangement which can be compressed, will not resume its initial shape and is not removeable from the load. On impact at a point on its edge, at least a portion of the impact component in the region of the point of impact is deformed and is able to approach the load, while the radial point located opposite to the point of impact may not be moved relative to the load due to the unremoveable support of the impact component on the load. The middle part of the impact component, which is directly coupled to the separating mechanism, also approaches the load as a result of the impact induced distortion of the edge region of the impact component. It has been found desirable for the impact component, at its edge to have a distance of movement of more than double the movement of the part thereof which will cause actuation of the separating mechanism. Accordingly, the distance of movement of the impact component in the middle required for the operation of the separating mechanism will be less than the maximum distance of movement of an edge region deformed as it acts as a shock absorber. The unremoveable connection between the impact component and load can be effected according to the invention by a number of bolts distributed over the circumference thereof which are provided with flexible counter pressure devices, for example pressure springs or workable synthetic casings or a circumferential bracket of deformable material such as sheet metal or synthetics which extend between the impact component and load. The counter pressure device or devices will be selected with regard to energy consumption when the coupling mechanism function as a landing shock absorber.
Compression springs may be provided on the belts or on rope loop extensions of the belt ends, such springs being stretched in the impacted condition to pull the released belts out of the connecting area in order to allow the freeing of the load from the belt assembly.
So that the belt ends cannot be trapped between the plate-shaped impact component and the load, the belt ends are advantageously positioned in protected belt guides. These belt guides may, for example, take the form of grooves formed on the bottom surface of the load or defined by projections extending from the surface of the load.